This invention relates to a downhole profile formation, and in particular the formation or provision of profiles in cased boreholes. The invention also relates to cutting or otherwise forming casing.
In the oil and gas exploration and production industries, subsurface hydrocarbon-bearing formations are accessed via drilled boreholes lined with steel tubing, known as casing. The casing will often define profiles, typically annular recesses or annular restrictions, to facilitate the location and mounting of tools and devices in the borehole. The profiles are formed in the casing before it is run into the borehole, and are positioned in the string of casing at predetermined locations. This places restrictions on the subsequent placement of tools and devices in the bore, and the original profile locations may prove not to be appropriate as the well is developed. Further, different tool manufacturers utilise different profiles, and once the casing is in place an operator may be committed to obtaining tools from a single source throughout the life of the well.
It is among the objectives of embodiments of the invention to obviate and mitigate these difficulties.
According to a first aspect of the present invention there is provided a method of forming a profile in a section of tubing, the method comprising:
providing an expander device having at least one radially extendable expander member;
positioning the device at a predetermined location in a section of tubing;
extending the member to deform the tubing at said location to create a profile therein.
The invention facilitates the formation of a profile at a desired location in a section of tubing, such that, for example, an operator is not constrained to utilising preformed profiles of particular configuration at fixed locations in the tubing.
The profile may take any appropriate form, including one or more annular recesses, one or more circumferentially spaced recesses, and a female thread. As such, the profile may permit or facilitate the location of tools or devices in the tubing at the profile location. Alternatively, the profile may serve as a reference point.
Preferably, the tubing is deformed by rolling expansion, that is an expander member is rotated within the tubing with a face in rolling contact with an internal face of the tubing. Such rolling expansion may cause compressive plastic deformation of the tubing and a localised reduction in wall thickness resulting in a subsequent increase in tubing diameter. Alternatively, where the tubing is constrained, for example by outer tubing or surrounding rock or cement, the tubing material may flow by virtue of the compressive plastic deformation to create a groove or raised profile. The tubing expander may take any appropriate form, and the expander member may be mechanically or fluid pressure activated. Conveniently, the expander member is in the form of a roller, and may define a raised circumferential rib or other profile to provide a high pressure contact area and to create a profile in the tubing of a predetermined form. Preferably, the expander member is extended by application of fluid pressure. In the preferred form, the expander member is in the form of a roller having a tapered end and is operatively associated with an axially movable piston and cam or wedge, although in other embodiments the member may itself define a piston which is radially movable in response to internal expander tool pressure. Preferably, a plurality of expander members are provided, and most preferably a plurality of the expander members are radially extendable.
Preferably, the member is run into the tubing on a running string, which may be reelable, such as coil tubing. The running string may be rotated to create the profile, or a motor may be mounted in the running string to rotate the expander.
The tubing may be in the form of a riser tube, as used to connect an offshore platform, rig or ship to a subsea wellhead assembly. Alternatively, the tubing may be in the form of bore-lining tubing, such as casing or liner, or may be production tubing.
According to a second aspect of the present invention there is provided a method of forming a profile in a section of tubing, the method comprising deforming a section of tubing by rolling expansion to create a profile therein.
According to another aspect of the present invention there is provided a method of providing a profile in a section of tubing, the method comprising:
providing a ring of deformable material;
providing an expander device having at least one radially extendable member;
positioning the ring and the device at a predetermined location in a section of tubing;
extending the member to deform the ring such that the ring engages the tubing at said location to create a profile therein.
According to a further aspect of the present invention there is provided apparatus for providing a profile in a section of tubing, the apparatus comprising: a ring of deformable material; and an expander device having at least one radially extendable member, the device being locatable within the ring and the member being extendable to deform the ring into engagement with surrounding tubing to create a profile therein.
These aspects of the invention offers additional advantages to the aspects of the invention described above. In certain applications it may be difficult to deform existing tubing, which would be the case with, for example, heavy gauge cemented casing or hardened tubing, and these aspects of the invention obviate these difficulties by locating a ring in the casing. Further, the ring may provide a restriction in the tubing, which may be utilised as a xe2x80x9cno-goxe2x80x9d to locate tools and other devices in the tubing. The ring may be preformed to define any predetermined profile, for example a thread, lip, recess or wedge.
Preferably, the ring and the expander device are run into the tubing together. Most preferably, the expander member is profiled to provide a mounting for the ring.
Preferably, the ring is deformed to form an interference fit with the tubing, most preferably by increasing the diameter of a section of the ring. Most preferably, the ring is deformed by rolling expansion, that is an expander member is rotated within the ring with a face in rolling contact with an internal face of the ring. Such rolling expansion causes compressive plastic deformation or yield of the ring and a localised reduction in wall thickness resulting in a subsequent increase in ring diameter.
The ring may comprise a relatively ductile portion welded or otherwise connected to a relatively inflexible portion, the deformation of the ring being restricted to the relatively ductile portion.
The ring may carry grip banding or the like on an outer surface to facilitate secure location relative to the tubing. The grip banding may comprise relatively hard elements such as grit or balls formed of hard material such as tungsten carbide.
According to yet another aspect of the present invention there is provided a method of providing a profile in a section of tubing, the method comprising deforming a ring of material by rolling expansion within a section of tubing such that the ring engages the tubing at said location to create a profile therein.
According to a still further aspect of the present invention there is provided a method of cutting a section of tubing, the method comprising:
providing a cutting device having at least one radially extendable rolling member defining a raised circumferential portion;
positioning the device at a predetermined location in a section of tubing;
extending the member to contact the tubing at said location and rotating the device to deform the tubing, the degree of deformation being such that the tubing is cut at said location.
This aspect of the invention may be used in many different applications, for example severing a riser which cannot be released from a wellhead assembly, or cutting a section of casing or liner.
Preferably, the cutting device is provided with a plurality of rolling members, which progressively compress the tubing wall and reduce the wall thickness thereof.
These and other aspects of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a schematic sectional view of a stage in a method of forming a profile in a section of tubing in accordance with an embodiment of an aspect of the present invention;
FIGS. 2 and 3 are schematic sectional views of stages in a method of providing a profile in a section of tubing in accordance with an embodiment of another aspect of the present invention;
FIGS. 4, 5 and 6 are schematic sectional views of stages in a method of providing a profile in a section of tubing in accordance with a second embodiment of said another aspect of the present invention; and
FIG. 7 is a schematic sectional view of a stage in a method of cutting tubing in accordance with an embodiment of a further aspect of the present invention (on same sheet as FIG. 1).